Tension indicator for threads on sewing machines



Dec. 28 1948.

A. H. LARSON ET AL Filed Jan. 22, 1946 TENSION INDICATOR FOR THREADS ON SEWING MACHINE S fl erfffzar 0/2 C/f a r/ea M1 521 M/ZM Patented Dec. 28, 1948 TENSION INDICATOR FOR THREADS ON SEWING MACHINES Albert Larson and Shades Fox, El Dorado, 'Ark.

Application January 22, 1946, Serial No. 642,760

This invention relates to a device for indicating. the correct tensioning of threads in sewing machines.

It is an object of the invention to provide a device which may be readily secured to threads in sewing machines, and which will indicate whether the tensioning of said threads is too loose, too tight, or correct.

It is a further object of the invention to provide a device of the above character which is simple to operate, rugged and free from maintenance difficulties, which is constructed of relatively few easily fabricated parts, and which is readily assembled and disassembled.

The general objectives to be attained by this invention when used in conjunction with sewing machines are to assure an even-tie of the threads, to eliminate loose or loop stitches, wrinkles, drawn or pulled seams and material, breaking of threads, straight thread stitches, ripped out seams and waste of time and material aswell as expensive service calls. All the above evils, as well as others, are largely due to improper thread tensions in sewing machines, and the proper and frequent use of this inventionwill result in proper adjustment of thread tensions, and consequent obviation of the difliculties.

With the above and still further objects, as will hereinafter more fully appear, one embodiment of the invention is described in the following specifications, and illustrated in the accompanying drawings, and the invention is particularly pointed out and defined in the appended claims. Reference is had to the drawings, wherein like numerals of reference apply to the same parts throughout the various figures, and wherein:

Figure 1 is a front elevation of the device;

Figure 2; is a side view, in elevation, of Figure 1;

Figure 3 is a rear elevation of the device;

Figure 4 is a transverse section; taken on a median line of the device;

Figure 5 is a front view of the device with the front cover removed; and

Figure 6 is a view of a detail of the invention.

Referring now to the drawings in detail, it will be observed that the case of the instrument consists of two parts, a front half I and a rearward half 2, secured or jointed by means of bolts 3, which extend through holes extending through the rearward half of the case and which engage with threaded holes provided in the front half of the case.

Provided in the rearward face of casing section I is a recess 4 which slidably receives a fiat control bar 5'; provided at one end with a hole 5 having a small V-slot I formed in its circumference 2 Claims, (Cl. 23-143) 5 I Y 2 and directed toward the tying a knot in the thread, inserting the knot through the hole 6 and pulling same tightly into the V-slot I.

/ At the end opposite to that containing hole 6, the bar 5 is provided with a slot 8 and a pin-9 positioned at one side of the slot. fits slidably over the portion of a rotatable shaft II within'an annular recess Ill. The shaft is providedwith a diametrical hole 24 at one side of annular'recess I0, and a spring I2, having ap proximatelya U-shape, and comprising a bulge, I3 in one leg thereof, has its straight leg inserted, through hole 24 and its bulged leg embracing theannular enlargement I4 of shaft II.

. The spring clip projects to one side of the shaft and provides between the portions of theleg s adjacent the closed end thereof a guide slot for the pin 9, which extends therebetween.

A second annular shaft enlargement I6 at the opposite side of recess Ill from enlargement I4 is provided with a hole II, into which is secured one end of a coil spring I8 which surrounds the shoulder I6, the other end of spring IB being secured to the rearward casing section 2, at 25.

This construction serves to provide a force resiliently urging the bar 5 inwardly of the casing.

The shaft I I is journalled at one end in a bearing I9 located centrally of the front casing section I, and at its opposite end in a well 20 provided in a boss 2I which is located centrally of the rearward casing section 2, end thrust being taken up by steel ball 26 located in boss 2I between the bottom of well 20 and the corresponding end of shaft II.

Pressed on an end of shaft I I which extends slightly beyond the front face 22 of the indicator casing is an indicator pointer 23. An unbreakable crystal 2! is pressed into an annular shoulder in the casing section I to cover the pointer 23, as well as the face 22 of the indicator, upon which is provided suitable dial 24.

In assembling the device from its component parts, the recessed portion I0 of shaft II is inserted in slot 8 of bar 5 so that pin 9 extends adjacent to hole 24. The straight side of spring clip I2 is inserted in hole 24 with pin 9 between the legs of the spring clip adjacent the closed end thereof. An end of spring I8 is inserted in hole I! of annular shoulder I6 and the assembly consisting of shaft II and bar, 5 and its associated springs I2 and I8 appliedto casing half 2 slipping the spring I8 over the boss 2| and the shaft end II in the well 20, after insertion therein of ball adjacent end ofthe bar.- Threads may be attached to the indicator 'by The slot, 8 1

I. The tail end of spring [8 is now secured to point 25 of the casing section 2, which may involve a small hole in the casing. The front casing section is now applied with hearing l9 over the corresponding end of shaft II, and bolts 3 are inserted and tightened. Pointer 23 is now pressed on shaft I I so that it points to the lowest part of scale II when bar 5 is at its limiting position within the casing. Crystal 21 is next pressed into the annular seat provided therefor to complete the assembly.

In utilizing the indicator of this deviee to ade- Just sewing machines, the sewing machlnfi' is threaded and about two inches are sewed. The presser foot of the machine is then raised and the material being sewed is removed. The Bob bin thread is attached to the tension indicator and pulled slowly toward the operator. The bobbin tension screw may then be adjusted until the indicator pointer indicates Correct. For adimhgirthe top thread tension, the presser foot-is dtoppod ahd thethread removed from' theneedle guides up to the thread takeup lever, then thUthrea'd is"-attachedto the tension indicator and pulled slowly thereby through the t'akeup' 1am: The upper tension regulator may then lfi ddjusted until the indicator pointer' reads Gorhiot.

Whatfweclaiin is:

l. M-thread'tenslon indicator comprising a casmg havin a front section provided with a centrfil dpe'n'ing, and a rear section provided wan a rrlflfii'nal recess and' a hollow centralbo'ss, a sliaft jiiuri'idld a t one end" in said central opening and ai't' its opposite end in said boss and having an annular recess intermediate the length thereof add tranverse' holes therethrough; one at each side of said annular recess, a flat control bar slidably received in said marginal recess having in one end an elongated slot receiving the an of said bar, a pin projecting from saidb'ar Number 4 verse hole in said shaft and a curved leg embracing said shaft and receiving said pin between the leg portions adjacent the closed end thereof to operatively connect said bar to said shaft, a coil spring having one end received in the other hole in said shaft and its other end secured to said casing, said coil spring surrounding saidQshaft andsaid boss and=applying a spring force to said shaft urging said bar inwardly of said casing, a dial on the outer face of said casiii'g front section, and a pointer secured on the correspondingend of said shaft overlying said dial 2. A thread tension indicator comprising a holrow casing having a marginal recess therein, a

shaft journaled in said casing, a dial on one outer faceofi' said casing, a pointer secured on said shaft overlying said dial, a control bar extending slidably through said marginal recess. means operatively connecting said control bar to said'shaft, and a coil spring connected at one end of'saidshaft and at its opposite end to'said casing and surrounding said shaft to rotate said shaft in a direction to urge said control bar inwardly of said casing, said means operatively connecting said" control bar to said shaft comprising a pin on sa'id'bar, and a U-shaped spring clip detachably secured to said shaft and receiving said pin between the portions of its legs adjacent the closed end thereof.

ALBERT H. LARSON. CHARLES W. FOX.

REFERENCES CITED The following. references are of record in the file of this patent:

STATES PATENTS Name Date Blakeslee Dec. 25, 1883 Emerson May- 19, 1891 Grimmel Aug. 2, 1898 FOREIGN PATENTS Country Date Great Britain 1906 Number 290,840; 452,602 603,5 18 

